Snippet

Decoupling Components with Application Events

Application events facilitate loose coupling between components. Instead of calling an email service directly from a registration service, you publish an event that interested listeners can handle independently.

snippet.java

java

public record UserRegisteredEvent(String email) {}
 
@Service
public class RegistrationService {
    @Autowired private ApplicationEventPublisher publisher;
 
    public void register(String email) {
        // Registration logic...
        publisher.publishEvent(new UserRegisteredEvent(email));
    }
}
 
@Component
public class EmailListener {
    @EventListener
    public void handleUserRegistration(UserRegisteredEvent event) {
        System.out.println("Sending welcome email to: " + event.email());
    }
}

spring

Breakdown

ApplicationEventPublisher

Spring interface used to broadcast events throughout the context.

publishEvent

Method to send an object as an event to all registered listeners.

@EventListener

Annotation that marks a method as an event handler for a specific type.

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Decoupling Components with Application Events

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